Stripping electrodeposited metal sheets



Spt. 21, 1943. I c. E. YATES STRIPPING ELECTRODEPOSITED METAL SHEET Filed June 22, 1940 2 Sheets-Sheet' l INVENTOR (bar/5 5 lazes BY 1 m, 74; MM

ATTORNEYS Sept. 21, 1943. c. E. YATES 2,330,103 I STRIPPING ELECTRODEPOSITED METAL SHEET I 2 Sheets-Sheet 2 Filed Jun 22, 1940 Patented Sept. 31, 194s Charles E. Yates, Perth Amboy, N. 3., assignpr to Anaconda Copper Mining tion of Montana,

Company, a corpora- Application June 22, 1940, Serial No. 341,889

1 Claims. ((1204-13) ducing such thin sheets,

This invention relates to stripping electrodeposited metal sheets from rotating cathodes, and provides an improved method and apparatus for continuously stripping such sheets. The invention is particularly adapted for use in stripping thin sheet copper from rotating cathodes, but is applicable to the continuous stripping of any electrodeposited metal.

A successful process for continuously producing thinsheet metal electrolytically has been in use for some time and has enabled the production of very: thin sheet metal in greater widths than can be produced by other means. This processas carried out for the manufacture of thin sheeticopper, for example", involves depositing the copper electrolytically on'the cylindrical surface of a rotating cathode drum which is partially immersed in,a suitable electrolyte.

stripped therefrom and is passed around a takeup roll. The copper sheet may be wound on the take-up roll or may be wound. on a separate roll to which the copper sheet is'passed from the take-up roll. The width of the sheet copper product is determinedby the width of the oathode face of the drum, and thickness of the sheet is governed by the speed atwhich the drum rotates. At relatively low speeds each unit. of area of the cathode is immersed in the electrolyte for arelatively long period of time per revolution of the drumyand in consequence a relatively thick deposit. is formed on the drum and a relatively thick sheetproduct is obtained. At higher speeds each unit of area of the cathode is immersed in the electrolyte for a relatively short period of time per revolution of the drum and only a relatlvely thin deposit of copper is formed thereon with the resultingproduction of a thin copper sheet. Sheet copper weighing as little as M; of an ounce per square foot (corresponding to a thickness of 0.00011 inch) and even less may be made by this process, and thicker sheets are readily produced.-

Coppersheets weighing about one ounce per square foot and upwards (upwards of about 0.00135 inch in thickness) may be stripped from the rotating cathode without particular difflculty, for example by passing the sheet from the oathode over acylindrical stripping roll or bar. With thinner sheets, however, stripping is very difflcult becausepf the ease with which the sheets tear at the edges, and a cylindricaLStripping roll or bar is not satisfactory for stripping these thinv v As the cathf ode rotates above the surface of the electrolyte,

the copper deposited oirthe cathode surfae is the varying degreesof adhesion of different local areas of the sheet, to

the cathode causes the stripped sheet, at the relatively high speed with which it is passed over a take-up or ironing roll for winding, to whip as it is stripped from the drum. This whipping ac- 1 tion of relatively thin sheet copper results in uneven distribution of the stripping strain imposed on the sheet being stripped from the rotating cathode and further produces wrinkles in the thin copper sheet. The unequal distribution of stripping strain across the width of such thin sheet copper tends to tear or rip this fragile sheet. A

tear not only spoils the product but causes'seriousdelays in production. The formation of wrinkles in the product detracts from the-appearance, and in some instances the utility, of I such thin sheet copper and makes it diiiicult to wind the sheet compactly and smoothly on a roll. Because of such dimculties as those noted here-- inabove in stripping very thin electrodeposited sheet copper, special means and great care have been required heretofore in the production of long lengths of copper sheet weighing less than about one ounce per square foot. 4

The present invention provides an improved method for continuously stripping a thin sheet of electrodeposited metal from a rotating cathode whichenables production of long lengths of such very thin sheet, metal without tearing-the sheet and without the formation of wrinkles therein. My new method of stripping involves ner sheets from the rotating cathode. In proto maintaining the stripped sheet substantially flat and wrinkle-free as it is removed'and withdrawn from the cathode whereby the stripping strain imposed on the sheet is distributed uniformly across the widththereof. The stripped sheet is maintained substantially flat and wrinkle-free by subjecting it to a spreading operation actingv from the central portionof the sheet-outwardly toward the edges thereof in such a manner that local areas of relatively high stripping strain are minimized. The development of tears is thereby minimized and a substantially wrinkle-free sheet is obtained which maybe wound compactly in the form of a roll. I

Suitable apparatus for carrying out the new method of my invention comprises a take-up roll for the stripped sheet mounted for rotation about its longitudinal axis with said axis arranged substantially parallel to the axis of rotation of a rotating cathode drum, and means for spreading the sheet: uniformly on' the take-up roll. The spreading means comprises spreading elements pressing against the surface of the sheet on the erence to the stripping of thin sheet copper.

sheet in such manner as to spread the sheet uni-- formly outwardly from the central portion of the sheet; toward the edges thereof. The take-up roll may serve as the winding roll or a separate winding roll may be providedto receive the spread sheet as it passes from the take-up roll.

A preferred embodiment of my invention is described hereinafter in detail with particular ref- In the following description reference is made to the accompanying drawings in which spreading elements shown in Fig. l; and

Fig. 6 is a detailed side view of the spreading elements shown in Fig. 1.

The apparatus shown in the drawings comprises a tank ||l containing a suitable electrolyte, such for example as an acid copper sulphate solution. A cathode drum H, which is partially immersed in the electrolyte, is mounted for rotation about its axis on a shaft |2 carried in a bearing l3. Anodes |4 curved to conform with the cylindrical cathode surface of the drum l I are mounted in the tank In below the surface of the electrolyte in fixed spaced relationship with the drum. Suitable electrical connections are made to the cathode drum and to the anodes for electrolyte to deposit on the drum.

The cathode surface of the drum H is prefer: ably of antimonial lead. The drum II is rotated in the direction of the arrow by means of a pulley |5 mounted on the shaft I2, and as the drum rotates copper is deposited upon the portion thereof below the surface of the electrolyte. The deposited copper is lifted in the form of a sheet from the exposed cathode surface of the drum upon rotation of the drum above the surface of the electrolyte. The stripped copper sheet I6 is passed over a take-up roll I! (as shown in Fig. 1) mounted for rotation on a shaft Hi. The copper sheet is wound upon a winding reel mounted for rotation about shaft 2| driven by a wheel 22 in such a manner as to maintain the proper winding tension required to strip the sheet from the rotating cathode drum.

The take-up roll H and the winding roll 20 (Figs. 3 and 4) preferably are of a length approximately equal tothe'width of the copper sheet I6 stripped from the rotating cathode. ing roll is supported adjacent the ends of shaft 2| by brackets 23 mounted on the frame 24, each bracket being provided with a cut-away portion 25 of sufficient width to permit entry of the shaft 2| of the winding roll and to permit insertion or withdrawal of the shaft of a winding roll from the brackets when a fresh winding roll is to be substituted for a fully wound winding roll. The

position of the winding roll is such that its axis .40 the purpose of causing copper in solution in the vantage directly above the take-up roll H. The two spreading units are substantially identical, each comprising an endless conveyor such as the sprocket chain 26 mounted on sprocket wheels 21 and 28. The sprocket wheel 21 of each unit adjacent the frame 24 is mounted for rotation ,on a shaft 29 with the sprocket wheel 21 positioned at one end of the shaft and with a bevel gear 39 mounted on the other end of the shaft 29. These outermost sprocket wheels 21 are driven by means of bevel gears 3| engaging bevel gears 36 and mounted on a drive shaft 32 to which driving power is delivered through the driving wheel 33. The drive shaft 32 is mounted adjacent each end thereof in a cylindrical bearing section 34 which is supported from the horizontal section of frame 24 by means of the supporting member 35 mounted on the frame.

The drive shaft 32 is provided with a cylindrical sleeve 36 extending between, but out of contact with, the bevel gears 3|. Brackets 31 secured to sleeve 36 near the opposite ends thereof are also secured to cylindrical bearing sections 38 in which the sprocket wheel shafts 29 are mounted. The innermost sprocket wheel 28 of each spreading unit, these wheels being positioned near the mid-point between the frames 24, are mounted on shafts 40 which are supported for free rotation within cylindrical bearing members 4|. The bearing members 4| are secured, as by welding at 42, on the drive shaft sleeve 36. Thus, it will be seen that each of the sprocket wheels 21 and 28 is mounted on a shaft which is supported by a cylindrical bearing member (38 and 4|, respectively) which is, in turn, secured, at its end opposite the sprocket wheels, to the sleeve 36,. In accordance with this construction, the outermost sprocket wheels 21 are driven by power transmitted through the drive shaft 32 and the bevelgears 30 and 3|, and all of the sprocket wheels 21 and 28, with the endless conveyor mounted thereon, are pivotally mounted or hinged about the shaft 32 by means of the sleeve with the brackets held in transverse spaced relationship in the sprocket chain by means of the spacing elements 46. The rubber tube 43 is secured to the flanges 45 by suitable means such as bolts 41. i a

A different type of spreading element may be v the like, supported in caster mountings may be The windsubstituted for the rubber tubes 43. The caster mountings permit the wheel to travel transversely across the moving metal sheet without scratching or rubbing the surface-of the sheet, spreading action being obtained by providing t e wheels with a controlled braking action. The caster-type mounting for the wheels is not necessary but permits the spreading wheels to adjust themselves to variations in the relative speeds of their transverse movement and the longitudinal or forward movement of the metal sheet so hat the wheels spread the sheet, without scratching the sheet, by their braked rolling in a direction determined by the components of their speed transversely and longitudinally of the sheet.

The take-up. roll I! is held in fixed spaced relationship with the spreading units by means of the depending brackets 48 which are secured,

as by welding or other suitable means, to. the bearing members 38. The brackets 48 are provided. at their. extremities, directly below the outermost sprocket wheels 21 of the spreading units, with cylindrical bearing sections 50 for mounting the shaft i8 of the take-up roll 11 in suitable bearings. v

The spreading unit drive shaft 32 and the take-up roll 20 are driven by means of an endless belt or a sprocket chain which passes from a suitable power source around the drive 'wheel 33 mounted on the spreading unit drive shaft'32, thence around an idling wheel 52 mounted on the frame 24 for rotation about an axis substantially parallel to the axisof rotationof the winding rouzt and the driving wheel 33.

The take-up roll may comprise the winding roll 20 as shown in the modification of my apparatus illustrated in Fig. 2. In this modification the winding roll 20 is supported by the bracket 23 and is mounted for rotation about an axis (shaft 2|) substantially parallel with the axis of rotation of the cathode drum l land is positioned directly below the spreading units. w

The spreading elements 43 press against the surface of the copper sheet on the take-up roll tained between the spreading elements and the metal sheet on the take-up roll (winding roll 20) by the constant weight of the spreadingunits I which are free to move vertically with variations 22 of the winding roll, around the drive wheel inthe thickness of the winding roll as the metal sheet. is woundthereon.

When commencing production of copper sheet,

a relatively thick deposit of copper is formed on the cathode surface of the drum. A thick de-' posit may be stripped initially by hand without much trouble. The free end of the sheet thus. stripped is passed over the take-up roll 11- and is secured'to the winding roll 20 as shown in Fig. 1, or the free end of the sheet may be passed over and secured to the" winding roll 20 when-the winding roll is employed as the take-up roll as shown in Fig. 2. Thenceforward the entire oper l ation may be automatic; 7 By means of the stripping method and apparatus provided by this invention it is possible continuously to strip long copper weighing of an ounce per square foot and less. My new stripping method and apparatus uniformly distributes thev stripping strain across the widthof such thin metal sheet whereby local-areas of relatively high' strain are minimized with the resulting substantial elimination of tears in the stripped metal sheet resulting from uneven distribution of stripping strain across the width of the sheet. Furthermore, the new stripping method and apparatus of my in-' vention facilitate the winding of thin electrodeposited metal sheet on a winding roll ,by eliminating wrinkles which form when an uneven stripping strain is applied tothe sheet and, ac,-

cordingly, make it possible toproduce smooth-- ly.wound rolls of very thin sheet metal. My new stripping method and apparatus, by unlformly distributing the stripping strain imposed on the thin metal sheet, enable the use of sub.'

stantially higher stripping tension than could be The speed of the spreading elements 43 in frictional contact with the-stripped copper sheet may be maintained with particular advantage about fifteen times as great as the forward movement of the stripped sheet from the rotating cathode drum l'l toward and around the take-up roll IL. However, lesser. or greater relative speeds between the lateral movement of the spreading v ward movement of the stripped copper sheet may be used with advantage, the relative speed of 15:1 referred to above being particularly'desirable and effective in the stripping of very thin "copper sheet weighing about $4; of an ounce, or

less,per square foot (thicknesses of about 0.0004 inch or less).

In the apparatus shown in Figs. 1', 3 and 4, thespreading units and the take-up roll I! are maintained in fixed spaced relationship to one another. pable of pivotal movement on the sleeve 36 in an arc struck from this sleeve so that take-up roll I! is supported on the surface of the metal sheet wound on the winding roll 20, and yet is free to move vertically with variations in the thickness of the roll of metal sheet as the sheet is being wound on the winding roll:

However. both of these elements are caelements and the longitudinal or for ing elements pressing against the surface of the.

In the modification of my novel apparatus I shown in Fig. 2 wherein the winding roll 20 'serves the function of a take-up roll, the spreading";

units are sleeve on drive shaft also free to move pivotally about the 32. In thismanner, uniused heretofore with resulting improvements in the stripping of such thin metal sheet from a rotating cathode-drum.

, Iclaim:

1. The method of continuously stripping a thin sheet of electrodeposited metal' from a rotating cathode with production of long lengths of such thin sheebwithout tearing thereof which comprises winding the sheet on a roll under such tension as to strip the sh t from the cathode,

and subjecting the stripped sheet while substantially flat and undersaidst ipping tension to a spreading operation in su manner that the stripping tension is dist r1 uted uniformly across the width of the sheet in such a manner that local areas of. relatively. high stripping strain are eliminated and that a substantially wrinklefree sheet is obtained.

- 2. Apparatus for continuously stripping a thin sheet of electrodeposited metal from a rotating cathode drum comprising a take-up roll for the sheet mounted for rotation about its longitudinal axis with ,said axis arranged substantially parallel to the'drum axis of rotation, and spread! sheet on the take-up roll in such manner as to spread the sheet uniformly outwardly from the central portion bf the sheet toward the edges of the sheet.

3. Apparatus for continuously stripping a thin .sheet of electrodeposited metal from a rotating cathode drum with production of long lengths' form pressure for. frictional engagement is mainlengths of very light weight electrodeposited sheet metal such as sheet of such thin sheet without tearing thereof comprising spreading elements frictionally engaging the stripped sheet in such manner as to spread the sheet uniformly outwardly from the central portion of the sheet toward the edges of the sheet and to distribute stripping tension on the stripped sheet uniformly across the width of the lel to the drum axis of rotation, and spreading elements frictionally engaging the sheet on the take-up roll and arranged to move in frictional contact with the sheet from the central portion thereof outwardly toward the edges of the sheet.

5. Apparatus for continuously stripping a thin sheet of electrodeposited metal from a rotating cathode drum comprising a take-up roll for the sheet mounted for rotation about its longitudinal axis with said axis arranged substantially parallel to the drum axis of rotation, two spreading units each having a plurality of spreading elements mounted on an endless conveyor in such manner that at all times at least one spreading element of each unit is in position to engage frictionally a sheet on the take-up roll;

the spreading elements of each unit in position for frictional engagement with the sheet move in a direction substantially perpendicular to the direction of movement of the sheet and from the central portion of the sheet outwardly toward the opposite edges thereof.

6. Apparatus for continuously stripping a thin sheet of electrodeposited metal from a rotating cathode drum comprising a frame, a winding roll for the sheet mounted on the frame for rotation about its longitudinal axis, a shaft mounted on the frame substantially parallel to the longitudinal axis of the winding roll, a take-up roll for receiving the sheet from the cathode drum and for passing the sheet to the winding roll, the take-uptroll bearing upon the surface of the sheet wound on the winding roll and being mounted for rotation about an axis substantially parallel to the longitudinal axis of the winding roll, means for permitting pivotal movement of the take-up roll in an arc about the shaft, and spreading elements in fixed relationship with the take-up roll and frictionally engaging the sheet in contact with the take-up roll.

7. Apparatus for continuously stripping a thin sheet of electrodeposited metal from a rotating cathode drum comprising a frame, a winding roll on which the sheet is wound, said roll being mounted on the frame for rotation about its longitudinal axis, means for rotating the roll in such manner as to pull the sheet from the cathode drum, a shaft mounted on the frame substantially parallel to the longitudinal axis of the winding roll, spreading elements bearing upon the sheet being wound on the roll and adapted to move in frictional contact with the sheet from the central portion of the sheet outwardly toward the edges thereof, and means for permitting pivotal movement of the spreading elements in an are about the shaft.

CHARLES E. YATES. 

